In addition to Monahan, Kent Hughes acquired a first-round pick in exchange for future considerations. A real steal, in my opinion.
Costa Rontzocos has proposed a similar trade, this time for Anthony Mantha in Washington. Mantha is in the last year of his contract at $5.7 million, and Kent Hughes has enough cap space to accommodate his full salary.
If the Capitals have a player in mind and want to free up some cap space, this could certainly be a possibility. Alex Ovechkin is getting older, so why not make a push and try to make the playoffs one more time?
Moreover, if Mantha wants to sign another contract after this season, he'll need to step up his game, and Martin St-Louis is certainly an ideal candidate to help him in that regard.